layout: default title: ExtractMVP_EK60_Peaks parent: Grid Tools nav_order: 25 —

ExtractMVP_EK60_Peaks

Description

ExtractMVP_EK60_Peaks is a specialized post-processing utility designed to analyze the ASCII output files from cutMVPLocationSections. It automates the process of “picking” the depths of significant features from co-located vertical profiles of Sound Velocity (from MVP data) and acoustic backscatter (from an EK60 echosounder). For each input file, it identifies a single depth for a specified feature in the sound velocity profile and a single depth for a peak in a chosen backscatter trace, then outputs these two depths.

This tool is part of a workflow for tracking specific oceanographic layers (e.g., thermoclines, scattering layers) across a survey area.

Usage 

ExtractMVP_EK60_Peaks -outfile <output.ascii> -alltxtfiles <file1.txt> ... [OPTIONS]

Arguments

Option Description Default / Example
-outfile <output.ascii> Required. The path for the output ASCII file. Each line will contain an input filename, the picked sound velocity depth, and the picked EK60 depth. -outfile picked_depths.txt
-alltxtfiles <file1.txt> ... Required. Specifies one or more input ASCII profile files generated by cutMVPLocationSections. -alltxtfiles section1.txt section2.txt
-pickprof <index> Required. An integer (0-11) specifying which of the 12 available EK60 backscatter traces in the input file to analyze for peak detection. -pickprof 7
-minz <depth> Defines the minimum depth (in meters) of the vertical window to search within. The tool will ignore all data shallower than this depth. -minz 20
-maxz <depth> Defines the maximum depth (in meters) of the vertical window to search within. The tool will ignore all data deeper than this depth. -maxz 70
-SVpick_Upper_threshold <velocity> SV Picking Method. Sets the picking criteria for the sound velocity profile. The tool searches downwards from -minz and picks the depth of the first sample that drops below the specified <velocity> value (in m/s). This is used to find the top of a velocline. -SVpick_Upper_threshold 1495
-EKpick_Positive_peak <confidence> EK60 Picking Method. Sets the picking criteria for the backscatter profile. The tool finds the depth of the maximum backscatter value (the peak) within the search window. This peak is only considered valid if (peak_value - average_value) > confidence. This ensures that only significant acoustic peaks are chosen. -EKpick_Positive_peak 5.0
-v Enable verbose output during processing.  

How It Works

  1. File Iteration: The tool processes each input ASCII file specified by -alltxtfiles.
  2. Data Reading: For each file, it reads the vertical profile data, which includes depth, sound velocity, and EK60 backscatter traces.
  3. Sound Velocity (SV) Peak Picking (-SVpick_Upper_threshold):
    • It searches downwards from minz to maxz in the sound velocity profile.
    • The first depth at which the sound velocity falls below SVpick_Upper_threshold is marked as the SV pick.
  4. EK60 Backscatter Peak Picking (-EKpick_Positive_peak):
    • It identifies the maximum backscatter value within the specified pickprof trace between minz and maxz.
    • It also calculates the average backscatter within this window.
    • If the difference between the peak value and the average value exceeds EKpick_Positive_peak, the depth of this peak is marked as the EK60 pick.
  5. Output: For each input file, it writes the filename, the picked SV depth, and the picked EK60 depth to the -outfile.

Output Files

  • <output.ascii>: An ASCII file containing the picked depths for each input profile.

Dependencies

  • support.h: For general utility functions and error handling.

Notes

This tool streamlines the process of extracting specific oceanographic features from vertical profiles. The picking criteria are designed to be robust against noise and minor variations in the data. The two picking methods (SV threshold and EK60 positive peak) provide complementary ways to identify features based on different physical properties.